habitually lying or untruthful


US English

UK English

Part of Speech



Lying, deceptive, untruthful, fraudulent, dishonest, untrustworthy


Honest, truthful, trustworthy, credible, sincere

Word Forms

Part of Speech Words
Noun mendacity, mendacities
Verb None
Adjective mendacious
Adverb mendaciously

Example Sentences

  • The mendacious politician fabricated a web of lies to deceive the public and gain support.

  • With a mendacious smile, he spun a tale of success, concealing his true failures and shortcomings.

  • The mendacious witness distorted the truth, providing false testimony to protect the guilty party.

  • Her mendacious claims about her qualifications led to her downfall when the truth was revealed.


The word “mendacious” originates from the Latin term “mendax,” which means “lying” or “false.” It is formed by adding the suffix “-acious” to the root “menda-” or “mendax.” The prefix “men-” or “menda-” implies falsehood or deceit.

The usage of “mendacious” describes someone or something characterized by a tendency to lie, deceive, or be untruthful. It conveys a sense of deliberate falsehood, deceitfulness, or dishonesty in words, actions, or behavior. The term highlights a lack of trustworthiness and an inclination to mislead others.

As an adjective, “mendacious” emphasizes the untruthful nature of a person, statement, or situation. It is commonly used to describe individuals who habitually engage in lying, fabrication, or deception. The term is also applied to false or misleading information, misleading advertisements, or deceptive practices. The term can also be used to describe a system or culture that is based on lies and deception, such as a corrupt government or a fraudulent business.

Variations of the word “mendacious” include “mendaciously” as an adverb form and “mendacity” as a noun form.

Understanding the history and usage of “mendacious” reminds us of the importance of honesty and integrity in communication. It alerts us to the presence of falsehood and encourages critical thinking to discern truth from deception. Recognizing mendacious behavior can help protect us from being misled and promote a society built on trust and transparency.